code: def test_tf_device_scope(self):
      import tensorflow as tf
  
      if not tf.config.list_physical_devices("GPU"):
          self.skipTest("Need at least one GPU for testing")
  
      with backend.device_scope("cpu:0"):
          t = backend.numpy.ones((2, 1))
          self.assertIn("CPU:0", t.device)
      with backend.device_scope("CPU:0"):
          t = backend.numpy.ones((2, 1))
          self.assertIn("CPU:0", t.device)
  
      # When leaving the scope, the device should be back with gpu:0
      t = backend.numpy.ones((2, 1))
      self.assertIn("GPU:0", t.device)
  
      # Also verify the explicit gpu device
      with backend.device_scope("gpu:0"):
          t = backend.numpy.ones((2, 1))
          self.assertIn("GPU:0", t.device)
  
file_path: keras/keras/backend/tests/device_scope_test.py
imports: import pytest
  from keras import backend
  from keras import testing
label_desc: Use image node_id 1 for calling the DeviceTest obj's underlying member method code with example usage: obj.test_tf_device_scope() without return types